The members property is a list of (function, info_string,
output_labels) namedtuples. info_string describes what the
function does. output_labels is a list of names for each output.
category is a category in which the link function will appear (defaults
New link functions can be registered via
@link_function(info=”maps degrees to arcseconds”,
return degrees * 3600
Link functions are expected to receive and return numpy arrays